Ignition Coil Primary Control Circuit Low
The P2315 code indicates that the powertrain control module (PCM) has detected a low voltage condition in the primary control circuit of a specific ignition coil. This circuit controls the coil's ground path to fire the spark plug. A low voltage reading suggests excessive resistance, a short to ground, or a faulty coil driver. This can lead to misfires, reduced engine performance, and increased emissions.
01. Most Common Causes
- Faulty ignition coil
- Open or shorted wiring in the primary control circuit
- Poor electrical connection at the coil or PCM
- Failed PCM (rare)
02. Symptoms You Will Notice
- Check Engine Light on
- Engine misfire or rough idle
- Reduced power and acceleration
- Poor fuel economy
03. Step-by-Step Diagnosis
Step 1: Scan for codes and note which cylinder is affected.
Step 2: Visually inspect the ignition coil and wiring for damage or corrosion.
Step 3: Test the primary circuit resistance and voltage with a multimeter.
Step 4: Swap the suspect coil with another cylinder to see if the code follows.
Step 5: If wiring and coil are good, test the PCM output signal.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. Driving with a misfire can damage the catalytic converter and cause poor performance.
How much does it cost to fix?▼
Typically $50-$150 for a DIY coil replacement, or $100-$250 at a shop including diagnosis.